Induction Drugs (Ketamine) (Ex2) Flashcards

1
Q

What type of drug is ketamine?
What type of anesthesia does it produce?
What two properties does it possess?

A
  • Phenycyclidine derivative; NMDA receptor antagonist (PCP; “angel dust”)
  • Dissociative anesthesia (psychedelic)
  • Amnestic & intense analgesia
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2
Q

What signs and symptoms does dissociative anesthesia (ketamine) produce?

A

“Zonked” state

  • Non-communicative but awake
  • Hypertonus & purposeful movements
  • Eyes open but “no one’s home”.
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2
Q

What are ketamine’s two greatest advantages over propofol or etomidate?

A
  • No pain at injection (no propylene glycol)
  • Profound analgesia at sub-anesthetic doses.
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3
Q

What are the two greatest disadvantages of ketamine?

A
  • Emergence delirium
  • Abuse potential
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4
Q

What is Benzethonium Chloride? What is it’s relevance?

A
  • Ketamine preservative that inhibits ACh receptors
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5
Q

Differentiate S(+)Ketamine vs R(-)Ketamine.

A

S-Ketamine (left-handed isomer) is essentially better.

  • More intense analgesia
  • ↑metabolism & recovery
  • Less salivation
  • Lower emergence delirium
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6
Q

What benefits does a racemic ketamine mixture offer?

A
  • Less fatigue & cognitive impairment
  • Inhibits catecholamine reuptake at nerve endings (like cocaine).
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7
Q

What is Ketamine’s main mechanism of action?

A
  • Non-competitive inhibition of NMDA (N-methyl-D-aspartate) receptors and inhibits pre-synaptic release of glutamate.
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8
Q

What are Ketamine’s secondary receptor sites?

A
  • Weak GABAA effects.
  • Opioid (μ, δ, and κ)
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9
Q

What is Ketamine’s time of onset? (IV & IM)
When would this drug be utilized IM?

A
  • IV: 1 min
  • IM: 5 min (mostly for pediatric patients)
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10
Q

What is Ketamine’s duration of action?
What about its lipid solubility?
What is the result of this?

A
  • 10-20 min
  • Highly lipid soluble (5-10x greater than thiopental).
  • Results: Brain → non plasma bound → peripheral tissue.
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11
Q

What is the Vd and E½ time of ketamine?

A
  • Vd = 3L/kg
  • E ½ = 2-3 hours
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12
Q

Name the pharmacokinetic profile of ketamine:
- Clearance:
- Metabolism:
- Excretion:

A
  • Clearance: high hepatic clearance (1L/min)
  • Metabolism: CYP450’s.
  • Excretion: kidneys
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13
Q

What is the primary metabolite of ketamine and what its its significance?

A

Norketamine is metabolite (⅓ potency and prolongs analgesia).

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14
Q

In what patient population is ketamine tolerance most often seen?

A

Burn patients

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15
Q

What is the induction dose of ketamine IV?
What if it is given IM?

A
  • 0.5 - 1.5 mg/kg IV
  • 4 - 8 mg/kg IM
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16
Q

What is the maintenance dosing of ketamine?

A
  • 0.2 - 0.5 mg/kg IV
  • 4 - 8 mg/kg IM
17
Q

What is the subanesthetic/analgesic dose of ketamine?

A
  • 0.2 - 0.5 mg/kg IV
18
Q

What is the post-operative sedation and analgesia dosing for ketamine in pediatric cardiac surgery cases?

A

1-2 mg/kg/hour

19
Q

What is the neuraxial epidural analgesia dosing of ketamine?
What about intrathecal route?

A
  • 30mg epidural
  • 5 - 50 mg via intrathecal/spinal/subarachnoid
20
Q

Ketamine is a potent sialagogue. What does this mean for your clinical practice?

A
  • Manage excessive secretions during intubation & watch for coughing/laryngospasm.
21
Q

What drug and dosing should be used to treat excessive salivary secretions from ketamine administration?

A

Glycopyrrolate: 0.2mg

22
Q

You gave ketamine and the patient fell asleep within 30 seconds. If you gave no more doses when would you expect the patient to:
- Wake up?
- Be fully conscious?
- Start remembering things?

A
  • Wake up in 10-20 minutes
  • Full consciousness in 60 - 90 min
  • Amnestic effects should also wear off in 60 - 90 min.
23
Q

What patient populations is ketamine best used for?

A
  • Acutely hypovolemic patients
  • Asthmatics
  • Mental health patients
24
When would you do an IM induction of a patient?
- Uncooperative and difficult-to-manage mentally challenged patients.
25
Though ketamine has many indications, when should it be avoided?
- Patients with **pulmonary HTN and ↑ICP**.
26
What are Ketamine's effects on ICP? Why?
- ↑ICP via ↑CBF by 60% - **Potent cerebral vasodilator**.
27
At what dosing will the ICP increasing effects of ketamine plateau?
- 2mg/kg IV
28
Due to ketamine's increased excitatory EEG activity, how much does seizure potential increase with administration?
Trick question. **No increase in seizure potential with ketamine**.
29
What does the cardiovascular profile of ketamine look like? How can this side effect profile be blunted?
- SNS stimulation ( ↑ in sBP, PAP, HR, CO, etc.) - Blunted via pre-med with benzo's, volatiles, or nitrous.
30
Say you just gave ketamine and you have an unexpected drop in systolic BP and CO. What happened? How do you treat it?
- Depleted catecholamine stores - **Treat with direct-acting SNS agents (ex. phenylephrine)** vs indirect (ex. ephedrine).
31
What is the Pulmonary profile of ketamine?
- No depression of ventilation with CO₂ response maintained. - ↑ salivary excretion - **Intact upper airway tone & reflexes**. - **Bronchodilator with no histamine release**.
32
What does emergence delirium present like with ketamine?
- Visual, auditory, proprioceptive illusions. Morbid & vivid dreams up to 24 hours.
33
What is the proposed physiologic mechanism of action for emergence delirium occurrence with ketamine?
Depression of inferior colliculus & medial geniculate nucleus.
34
What percentage of patients will develop ketamine induced emergence delirium? How can it be prevented?
- Psychedelic effects in **5 - 30%** of patients. - **Pre-med with benzos**.
35
What "other system" effect does ketamine have?
- PLT aggregation inhibition
36
What are ketamine's most common drug interactions?
- Volatiles → hypotension - Non-depolarizing NMBs → enhancement - Succinylcholine → prolongation
37
Why does ketamine prolong succinylcholine's effects?
Ketamine is a plasma cholinesterase inhibitor.
38
Which induction agent has the highest analgesic properties?
- Ketamine
39
Why would ketamine be a decent induction drug for an OSA patient? Why not?
- Preservation of upper airway reflexes & ventilatory function. - Sialagogue.